188Rhenium skin cancer therapy: Two–year efficacy, safety and patient reported outcomes from the prospective, multicentre, phase IV, EPIC-Skin study in non-melanoma skin cancer

Background Non-melanoma skin cancers are the most common malignancies worldwide. While surgical excision achieves clearance rates exceeding 95%, treatment may be associated with disfigurement, functional morbidity, or be inappropriate for multiple lesions, anatomically difficult locations, patient comorbidities or preference. Lesion-directed therapy with the radioisotope 188 Re emits a highly localized dose distribution and rapid depth-dose falloff, enabling treatment of selected NMSCs. It is licenced in Europe, UK, Australia, NZ and Singapore as the medical device Rhenium Skin Cancer Therapy ( 188 Re-SCT). Treatment of NMSCs with 188 Re resin has been in clinical use since 2008, with retrospective series, pooled analyses, and prospective studies reporting high local control and favourable cosmetic outcomes. The present report represents the final EPIC-Skin analysis at 24 months follow-up. Methods This prospective, multicentre, single-arm phase IV study enrolled 189 adults, 187 with 1-3 biopsy-proven basal cell carcinoma or squamous cell carcinoma lesions ≤3 mm deep and ≤8 cm 2 . Participants received a single outpatient treatment with 188 Re-SCT delivering 50Gy to the deepest point of the lesion. Efficacy was assessed using modified visual Response Evaluation Criteria in Solid Tumours criteria, with the primary endpoint: the proportion of lesions achieving complete response (CR) during the study. Secondary outcomes included cosmesis, comfort, quality of life (QoL) and safety. Results Treatment of NMSCs with 188 Re-SCT achieved a CR rate of 95.1% during the study, with an additional 2.3% recurrence rate at 24 months. The most common 24-month Adverse Events of Interest were hypopigmentation (Grades 1/2: 58%/5%); telangiectasia (Grade 1: 15%); alopecia (Grades 1/2: 10.4%/0.9%) and induration (Grades 1/2: 9.6%/0.9%). Twelve Grade 3/4 events occurred at earlier time points, but none persisted at 12 months or after. Conclusions 188 Re-SCT demonstrates durable efficacy at 24 months follow-up, with a stable safety profile, favourable cosmesis and improved QoL. These results support 188 Re-SCT as a non-invasive treatment option for appropriately selected superficial NMSC.